Hydrogen is the main fuel source for power generation using fuel cells, but its storage and transportation present major issues. Currently, the storage of hydrogen is not commercially feasible. Also, current hydrogen production costs make fuel cell technology for power generation economically non-competitive when compared to traditional oil generation power systems. Current technologies are able to produce hydrogen at costs of between $5 to $6 per kg of H2, due to separation costs, high temperature and high pressure operating conditions, etc. Additionally, most current hydrogen production processes involve by-products such as NOx and COx, which are a hazard to the environment.
In many ways, ammonia is an ideal fuel for fuel cells and certainly shows some advantages as a precursor for hydrogen production. Ammonia represents a convenient way of securing supplies of hydrogen with one cylinder of ammonia yielding the equivalent to nine or ten cylinders of hydrogen. The fact that ammonia is easily condensed makes it a good choice for transportation and storage. Even though ammonia is flammable and toxic within defined limits, its presence can be detected by its characteristic odor. By catalytic cracking, the selectivity toward hydrogen production is very close to 100% and high purity hydrogen is obtained while nitrogen is removed by liquefaction. Ammonia is readily available and its decomposition by electro-oxidation in alkaline media is environmentally friendly with nitrogen and water as main products of reaction.
It appears that large current densities can be obtained from the oxidation of ammonia on noble metal but this electrode process is far less reversible than the oxidation of hydrogen. In the case of ammonia oxidation, anodic overpotentials can be as high as +0.5V on platinum black at ambient temperature and for current densities of 50 mA/cm2. Accordingly, a need exists for new electro-catalysts that will make electrodes more reversible and improve the kinetics toward ammonia oxidation. A need also exists for new environment-friendly electrolytic cells for hydrogen production.